[FieldTrip] excessive channel correlations
Smulders, F (PSYCHOLOGY)
f.smulders at maastrichtuniversity.nl
Fri Apr 13 16:45:50 CEST 2018
I have seen this occasionally, also on Brainvision's BrainAmp. I find it worrying, and would also like a good explanation. I have seen before that open channels on an AD converter just pass a copy of an occupied channel. So if you have a bad connection, that might explain it.
Subtracting the channel-average would possibly 'hide' a serious hardware problem, it seems to me that you just might end up with pure noise.
> On 13 Apr 2018, at 08:56, Eelke Spaak <e.spaak at donders.ru.nl> wrote:
> Hi Roy,
> I have no suggestion as to what might be causing this, but one
> suggestion on how to pragmatically deal with it, or at least maybe get
> some more insight.
>> - the problem is there regardless of reference montage (e.g., forehead and
>> averaged mastoids)
> Have you tried common average reference? If the signal is there on all
> channels, subtracting the common average should get rid of it.
>> - gel bridging, while theoretically possible, seems unlikely given that
>> literally all EEG channels are (almost) identical
>> We're still investigating but wanted to hear if anyone ever observed
>> anything like this? Were they able to solve it?
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
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